【Log4net 配置和使用】

1 NuGet包引入：Log4Net、 Microsoft.Extensions.Logging.Log4Net.AspNetCore、System.Data.SqlClient

2 添加 log4net.config 配置文件

<?xml version="1.0" encoding="utf-8"?>
<log4net>
	<!-- Define some output appenders -->
	<appender name="rollingAppender" type="log4net.Appender.RollingFileAppender">
		<file value="log4net\log.txt" />
		<!--追加日志内容-->
		<appendToFile value="true" />

		<!--防止多线程时不能写Log,官方说线程非安全-->
		<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />

		<!--可以为:Once|Size|Date|Composite-->
		<!--Composite为Size和Date的组合-->
		<rollingStyle value="Composite" />

		<!--当备份文件时,为文件名加的后缀-->
		<datePattern value="yyyyMMdd.TXT" />

		<!--日志最大个数,都是最新的-->
		<!--rollingStyle节点为Size时,只能有value个日志-->
		<!--rollingStyle节点为Composite时,每天有value个日志-->
		<maxSizeRollBackups value="30" />

		<!--可用的单位:KB|MB|GB-->
		<maximumFileSize value="3MB" />

		<!--置为true,当前最新日志文件名永远为file节中的名字-->
		<!-- 当将日期作为日志文件的名字时，必须将staticLogFileName的值设置为false -->
		<staticLogFileName value="true" />

		<!--输出级别在INFO和ERROR之间的日志-->
		<filter type="log4net.Filter.LevelRangeFilter">
			<param name="LevelMin" value="ALL" />
			<param name="LevelMax" value="FATAL" />
		</filter>
		<layout type="log4net.Layout.PatternLayout">
			<conversionPattern value="%date [%thread] %-5level %logger - %message%newline"/>
		</layout>
	</appender>

	<!--SQL数据库-->
	<appender name="AdoNetAppender_SqlServer" type="log4net.Appender.AdoNetAppender">
		<bufferSize value="1" />
		<connectionType value="System.Data.SqlClient.SqlConnection, System.Data.SqlClient, Version=4.6.1.3, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
		<connectionString value="data source=localhost;initial catalog=数据库名;integrated security=false;persist security info=True;User ID=账户;Password=密码" />
		<commandText value="INSERT INTO Log4Net ([Date],[Thread],[Level],[Logger],[Message],[Exception]) VALUES (@log_date, @thread, @log_level, @logger, @message, @exception)" />
		<parameter>
			<parameterName value="@log_date" />
			<dbType value="DateTime" />
			<layout type="log4net.Layout.RawTimeStampLayout" />
		</parameter>
		<parameter>
			<parameterName value="@thread" />
			<dbType value="String" />
			<size value="255" />
			<layout type="log4net.Layout.PatternLayout">
				<conversionPattern value="%thread" />
			</layout>
		</parameter>
		<parameter>
			<parameterName value="@log_level" />
			<dbType value="String" />
			<size value="50" />
			<layout type="log4net.Layout.PatternLayout">
				<conversionPattern value="%level" />
			</layout>
		</parameter>
		<parameter>
			<parameterName value="@logger" />
			<dbType value="String" />
			<size value="255" />
			<layout type="log4net.Layout.PatternLayout">
				<conversionPattern value="%logger" />
			</layout>
		</parameter>
		<parameter>
			<parameterName value="@message" />
			<dbType value="String" />
			<size value="4000" />
			<layout type="log4net.Layout.PatternLayout">
				<conversionPattern value="%message" />
			</layout>
		</parameter>
		<parameter>
			<parameterName value="@exception" />
			<dbType value="String" />
			<size value="2000" />
			<layout type="log4net.Layout.ExceptionLayout" />
		</parameter>
	</appender>
	
	<root>
		<priority value="ALL"/>
		<!--日志级别（从低到高）：ALL|DEBUG|INFO|WARN|ERROR|FATAL|OFF-->
		<level value="ALL"/>
		<appender-ref ref="rollingAppender" />
		<!--SQL数据库-->
		<appender-ref ref="AdoNetAppender_SqlServer" />
	</root>
</log4net>

3 Program.cs中注册

4 构造函数中注入得到实例并写日志

 使用实例写日志，日志示例：

运行后，写到文件中的日志，与数据库中的日志是一样的。

注：数据库脚本： 

USE [数据库名]
GO

/****** Object:  Table [dbo].[Log4Net]    Script Date: 2022-02-22 00:48:20 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Log4Net](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[Date] [datetime] NULL,
	[Thread] [nvarchar](50) NULL,
	[Level] [nvarchar](50) NULL,
	[Logger] [nvarchar](50) NULL,
	[Message] [nvarchar](max) NULL,
	[Exception] [nvarchar](max) NULL,
 CONSTRAINT [PK_Log4Net] PRIMARY KEY CLUSTERED 
(
	[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

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